In many consumer and industrial application, there is a desire or need to analyze the spectral composition of incoming light. Ultraviolet (UV), near-infrared and visible portions of the spectrum are often of high interest. An example application is a UV sensor, which could be placed on or integrated in a mobile phone or other device to provide an alert if a person has been exposed to a particular level of UV radiation in a particular time. Some such sensors can be complex in configuration and operation, for example interfacing with other systems such as GPS and weather, while others are more rudimentary and simply provide information regarding light spectral distribution.
Conventional sensors, however, are complicated to produce. These sensors often require multiple different spectral responses in order to measure the multiple different parts of incoming light. Multiple spectral responses, however, require multiple lithographic processes during semiconductor fabrication, which is expensive.
Therefore, there is a need for improved photo cells.